The present invention is directed to a gas swirling device for improved mixing of air and fuel in an internal combustion engine and more particularly to an economical gas swirling device disposed in an air conduit between an air filter and an engine air-intake manifold and having a plurality of vanes to cause swirling of a gas downstream from the device.
In internal combustion engines, including spark ignition-type automobile engines, it is well known that more complete mixing of air and fuel in the combustion chamber improves the ignition spark propagation, giving more complete combustion which, in turn, results in added power, lower emissions, and a more economical use of fuel. Improved fuel-air mixing by increasing swirl flow has been heretofore accomplished by the addition of expensive add-on hardware, such as mechanized turbo chargers or blowers, to an automobile engine. While installation of this kind will increase the power output of an engine, they are generally quite expensive and require the services of a skilled technician both for installation and on-going maintenance.
It is known that generating a swirling motion to an induction charge about the axis of an engine cylinder can have multiple benefits. A swirling motion imparted to the charge produces better charge preparation, and improves the combination of this charge within the combustion chamber. In a spark-ignition homogeneous engine operation, an increase in the cylinder charge rotative speed generally improves the burn rate and results in decreased fuel consumption. In stratified charge engines, swirling can promote mixing of the rich core of fuel in the surrounding air, to reduce exhaust emissions and fuel consumption. In diesel engines, swirling has long been used to promote fuel-air mixing for lower NOx emissions and soot formation.
Swirl rate is normally measured in terms of xe2x80x9cswirl numbersxe2x80x9d, normally defined as the ratio of in-cylinder charge rotative speed to engine rotative speed. Previously, engine xe2x80x9cswirl numbersxe2x80x9d have been improved by installing an air swirling device upstream of the engine air intake ports. Such devices, however, are typically either expensive add-on mechanical systems such as turbo charges or blowers, or add-on stator devices which are adapted to be used with a specific engine/carburetor or fuel injector combination, or alternatively adapted to be contained within a specially designed air filter. Add-on components such as turbochargers or blowers, while able to increase the power output of an engine, are quite expensive and require the services of a skilled technician both for initial installation and follow-on maintenance.
Several attempts have been made in the prior art to fashion a simple, easy to use, and inexpensive gas swirling device. While able to provide some increase in xe2x80x9cswirl numberxe2x80x9d when adapted to an automotive engine, these prior art devices all suffer from the particular defect of over-complexity. This has significant negative impact on their overall simplicity and manufacturing cost.
U.S. Pat. No. 4,962,642 discloses an air flow system which includes a stator device having a plurality of vanes which are disposed about the central axis of the air filter for causing an inlet air charge to swirl. However, the cross-sectional area of the disclosed stator device is sufficiently large to obstruct the engine air intake inlet, causing a pressure drop on the downstream side of the stator device with a consequent reduction of intake air volume.
U.S. Pat. No. 4,274,386 discloses a stationary fuel vaporization stator comprising a thin plate which is mounted between an autoclaimmotive engine carburetor and the opening of an intake manifold. Through-openings are provided in the plate which have the same outside diameter as the opening between the carburetor and the intake manifold, and a plurality of triangular shaped vanes are disposed about the circumference of the openings to help increase the turbulence of the fuel-air mixture while at the same time funneling any remaining liquid portion of the mixture toward the center of the opening of the plate. However, this device is only useful in carbureted engines, and must be constructed in multiple configurations so as to fit the various carburetor types provided on various make and model year automotive engines.
U.S. Pat. No. 5,113,838 disclosed an air swirl stator device adapted to be mounted along the central axis of an air filter. The stator device is a generally hollow cylinder and includes a plurality of vanes projecting into the cylinder for imparting a swirling motion to intake air. The stator device, however, is disclosed as functioning in combination with an annular shaped air filter and has a characteristic size and shape so as to fit in proper position. Moreover, the discloses stator device is difficult to manufacture; each vane is individually fashioned and separately mounted in a specific angular location along the inside wall of the stator""s cylindrical housing. Accordingly, several cutting and mounting operations are required to complete one device.
Commercially available swirling devices are assembled from many components spot welded or otherwise connected together. As such, the manufacturing costs associated with multiple part assemblies are too high.
Accordingly, it would be desirable to have an easy to manufacture gas swirling device that can be retro-fitted to existing automobile engines as well as installed in new ones. Advantageously, such a gas swirling device would have no moving parts, be easy to install and remove, would not require that any modifications be made to the automobile engine or its components, and be economical to manufacture. Such a gas swirling device would improve the xe2x80x9cswirl numberxe2x80x9d of an automotive engine but, at the same time, avoid any consequential reduction in air flow volume which could starve the engine of air and cause incomplete combustion and sluggishness.
A gas swirling device in accordance with the present invention is provided for use in an internal combustion engine. The device is adapted to be mounted in a flexible hollow air conduit between an air filter and an intake manifold or, alternatively, to be secured directly to, for example, a throttle body.
In one aspect of the present invention, the gas swirling device is formed from a single sheet of a flexible, bendable material into a substantially cylindrical body which is open at both ends. A plurality of stationary vanes are provided integral with and formed from the sidewall of the body, with each vane being disposed at an oblique angle with respect to a plane parallel to and passing through the body""s cylindrical axis.
In particular, each vane is constructed by cutting the body sidewall to from an incompletely severed trapezoidal portion which remains affixed to the body along an uncut side. The trapezoidal portion is deformed radially inwardly away from the body about an axis defined by the affixed side. The vane deformation axis defines an angle oblique to the cylindrical axis, such that, when deformed radially inwardly, each vane presents an interior face at an angle to a gas flow through the device, where the gas flow is in a direction parallel to the cylindrical axis.
In another aspect of the present invention, the circumference of the cylindrical body is not continuous but, rather, is split open along an axially extending seam to allow the housing of the air swirling device to circumferentially flex for fitting the cylinder into different sizes of openings. Retaining means are provided to allow the cylinder to be securely affixed to, for example, a throttle body. In particular, the retaining means may include tabs provided integral to and formed from the sidewall material of the throttle body and also include screw holes provided therethrough for screwing or bolting the gas swirling device in proper position over a throttle body.
In accordance with practice of principles of the present invention, the vanes provided integral with and formed from the cylindrical sidewall material of the body may be triangular in shape, trapezoidal, or rhombic. Regardless of shape, each vane is twisted concavely from a plane for smoothly changing the direction of air flowing across the concave surface of the blade.